System and method for an adaptive frame structure with filtered OFDM

ABSTRACT

Different filtered-orthogonal frequency division multiplexing (f-OFDM) frame formats may be used to achieve the spectrum flexibility. F-OFDM waveforms are generated by applying a pulse shaping digital filter to an orthogonal frequency division multiplexed (OFDM) signal. Different frame formats may be used to carry different traffic types as well as to adapt to characteristics of the channel, transmitter, receiver, or serving cell. The different frame formats may utilize different sub-carrier (SC) spacings and/or cyclic prefix (CP) lengths. In some embodiments, the different frame formats also utilize different symbol durations and/or transmission time interval (TTI) lengths.

This application is a continuation of U.S. patent application Ser. No.15/977,850 (now U.S. Pat. No. 10,200,172), filed on May 11, 2018 andentitled “System and Method for an Adaptive Frame Structure withFiltered OFDM” which is a continuation of U.S. patent application Ser.No. 15/004,430 (now U.S. Pat. No. 9,985,760), filed on Jan. 22, 2016 andentitled “System and Method for an Adaptive Frame Structure withFiltered OFDM,” which claims priority to U.S. Provisional ApplicationNo. 62/140,995, filed on Mar. 31, 2015 and entitled “System and Methodfor an Adaptive Frame Structure with Filtered OFDM,” all of whichapplications are hereby incorporated by reference herein as ifreproduced in their entireties.

TECHNICAL FIELD

The present invention relates to a system and method for wirelesscommunications, and, in particular embodiments, to a system and methodfor an adaptive frame structure with filtered orthogonal frequencydivision multiplexing (OFDM).

BACKGROUND

As mobile devices are increasingly used to access streaming video,mobile gaming, and other assorted services, next-generation wirelessnetworks may need to support diverse traffic types while also satisfyingoverall network and channel performance requirements. The differenttraffic types may have different characteristics, including differentquality of service (QoS) requirements (e.g., latency, packet loss,jitter, etc.). Accordingly, techniques for efficiently communicatingdiverse traffic types over resources of a wireless network are needed toenable next-generation wireless networks to satisfy the demands oftomorrow.

SUMMARY OF THE INVENTION

Technical advantages are generally achieved, by embodiments of thisdisclosure which describe a system and method for an adaptive framestructure with filtered OFDM.

In accordance with an embodiment, a method for transmitting signals in awireless network is provided. In this example, the method includestransmitting a first filtered-orthogonal frequency division multiplexing(f-OFDM) signal, and transmitting a second f-OFDM signal. The firstf-OFDM signal and the second f-OFDM signal are communicated inaccordance with different sub-carrier spacings than one another. Anapparatus for performing this method is also provided.

In accordance with another embodiment, a method for receiving signals ina wireless network is provided. In this example, the method includesreceiving a first filtered-orthogonal frequency division multiplexing(f-OFDM) signal, and receiving a second f-OFDM signal. The first f-OFDMsignal and the second f-OFDM signal are communicated in accordance withdifferent sub-carrier spacings than one another. An apparatus forperforming this method is also provided.

In accordance with an embodiment, a method for transmitting signals in awireless network is provided. In this example, the method includestransmitting, by a transmitter, a first transmission in a defaultsub-band with default orthogonal frequency divisional multiplexing(OFDM) parameters to a first user equipment (UE) when the UE initiallyaccesses a network, and transmitting, by the transmitter, higher-layersignaling to the first UE in the default sub-band. The higher-layersignaling indicates at least one first OFDM additional parameters andone second OFDM parameters. The first OFDM additional parametersincludes a first additional sub-band information and a first additionalframe structure parameters, and the second OFDM parameters includes asecond additional sub-band information and a second additional framestructure parameters. The first additional sub-band occupies a differentfrequency bandwidth partition than the second additional sub-band. Afirst sub-carrier spacing in the first additional frame structureparameters is different than a second sub-carrier spacing in the secondadditional frame structure parameters. The sub-carrier spacing in thedefault frame structure parameters comprises 15 kilohertz (kHz) and 30kHz, and each of the first sub-carrier spacing and the secondsub-carrier spacing is one from a predefined sub-carrier spacing set of7.5 kHz, 15 kHz, 30 kHz, and 60 kHz. In one example, the bandwidth ofthe first additional sub band and the second additional sub band is 5MHz. In the same example, or in another example, each of the firstadditional sub-band information and the second additional sub-bandinformation comprises an index of a sub-band or an offset from areference value associating with each sub-band. In any one of the aboveexamples, or in another example, each of the first additional framestructure parameters and the second additional frame structureparameters further comprises cyclic prefix (CP) length and transmissiontime intervals (TTIs). In any one of the above examples, or in anotherexample, the first additional frame structure parameters and the secondadditional frame structure parameters includes an index for eachsub-carrier spacing. In any one of the above examples, or in anotherexample, before the step of transmitting the first transmission, themethod further comprises continuously transmitting, by the transmitter,the default frame structure parameters in time; or periodicallytransmitting, by the transmitter, the default frame structureparameters. In any one of the above examples, or in another example, aframe format (e.g., the frame format 302 from FIG. 3) is assigned to asemi-static allocation period (e.g., the semi-static allocation period331), and another frame format (e.g., the frame format 309) is assignedto another semi-static allocation period (e.g., the semi-staticallocation period 332). In any one of the above examples, or in anotherexample, the default sub-band is a default filtered-orthogonalfrequency-division multiplexing (f-OFDM) sub-band, and the additionalsub-band is an additional f-OFDM sub-band.

In accordance with another embodiment, a method for transmitting signalsin a wireless network is provided. In this example, the method includestransmitting, by a transmitter, a first transmission in a defaultsub-band with default orthogonal frequency divisional multiplexing(OFDM) parameters to a first user equipment (UE) when the UE initiallyaccesses a network, and transmitting, by the transmitter, higher-layersignaling to the first UE in the default sub-band. The higher-layersignaling indicates at least a first set of alternative OFDM parametersand a second set of alternative OFDM parameters, the first set ofalternative OFDM parameters including at least a first alternativesub-band, and a first alternative frame structure, and the second set ofalternative OFDM parameters including a second alternative sub-band anda second alternative frame structure, wherein the first alternativesub-band occupies a different frequency bandwidth partition than thesecond alternative sub-band. The default frame structure parameterscomprises at least one of a 15 kilohertz (kHz) subcarrier spacing and 30kHz subcarrier spacing. The first frame structure and the second framestructure include one of a 7.5 kHz sub-carrier spacing, a 15 kHzsub-carrier spacing, a 30 kHz sub-carrier spacing, and a 60 kHzsub-carrier spacing. The first frame structure has a differentsub-carrier spacing than the second frame structure. In one example,each of the first sub-band and the second—sub-band have a 5 megahertz(MHz) bandwidth. In the same example, or in another example, each of thefirst sub-band and the second sub-band are associated with an index ofsub-band or offset from a reference value associating with eachsub-band, the index or the offset being indicating by the higher-layersignaling. In any one of the above examples, or in another example, eachof the first frame structure and the second frame structure comprisescyclic prefix (CP) length and transmission time intervals (TTIs). In anyone of the above examples, or in another example, the first plurality ofOFDM parameters includes a first index for a first sub-carrier spacingof the first frame structure, and wherein the second plurality of OFDMparameters includes a second index for a second sub-carrier spacing ofthe second frame structure. In such an example, the first sub-carrierspacing of the first frame structure may be different than the secondsub-carrier spacing of the second frame structure. In any one of theabove examples, or in another example, before the step of transmittingthe first transmission, the method further comprises continuouslytransmitting, by the transmitter, the default frame structure parametersin time. In any one of the above examples, or in another example, themethod further comprises periodically transmitting, by the transmitter,the default frame structure parameters. In any one of the aboveexamples, or in another example, the default sub-band is a defaultfiltered-orthogonal frequency-division multiplexing (f-OFDM) sub-band,and the first alternative sub-band is an alternative f-OFDM sub-band.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawing, in which:

FIG. 1 illustrates a diagram of an embodiment wireless network;

FIG. 2 illustrates a diagram of an embodiment filtered-orthogonalfrequency division multiplexing (f-OFDM) configuration;

FIG. 3 illustrates a diagram of another embodiment f-OFDM configuration;

FIG. 4 illustrates a flowchart of an embodiment method for transmittingf-OFDM signals having different frame formats;

FIG. 5 illustrates a flowchart of another embodiment method fortransmitting f-OFDM signals having different frame formats;

FIG. 6 illustrates a flowchart of an embodiment method for receivingf-OFDM signals having different frame formats;

FIG. 7 illustrates a diagram of an embodiment f-OFDM configuration;

FIG. 8 illustrates a diagram of another embodiment f-OFDM configuration;

FIG. 9 illustrates a diagram of yet another embodiment f-OFDMconfiguration;

FIG. 10 illustrates a flowchart of an embodiment method for configuringa downlink f-OFDM frame;

FIG. 11 illustrates a flowchart of an embodiment method for modifyingdownlink f-OFDM parameters;

FIG. 12 illustrates a flowchart of another embodiment method formodifying downlink f-OFDM parameters;

FIG. 13 illustrates a flowchart of yet another embodiment method formodifying downlink f-OFDM parameters;

FIG. 14 illustrates a flowchart of an embodiment method for configuringan uplink f-OFDM frame;

FIG. 15 illustrates a flowchart of another embodiment method fortransmitting an uplink f-OFDM frame in accordance with uplink f-OFDMparameters;

FIG. 16 illustrates a diagram of yet another embodiment f-OFDMconfiguration;

FIG. 17 illustrates a diagram of yet another embodiment f-OFDMconfiguration;

FIG. 18 illustrates a diagram of yet another embodiment f-OFDMconfiguration;

FIG. 19 illustrates a diagram of yet another embodiment f-OFDMconfiguration;

FIG. 20 illustrates an example of an intra-f-OFDM adaptive TTIconfiguration;

FIG. 21 illustrates a diagram of an embodiment communications device;and

FIG. 22 illustrates a diagram of an embodiment computing platform.

Corresponding numerals and symbols in the different figures generallyrefer to corresponding parts unless otherwise indicated. The figures aredrawn to clearly illustrate the relevant aspects of the embodiments andare not necessarily drawn to scale.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The structure, manufacture and use of the embodiments are discussed indetail below. It should be appreciated, however, that the presentinvention provides many applicable inventive concepts that can beembodied in a wide variety of specific contexts. The specificembodiments discussed are merely illustrative of specific ways to makeand use the invention, and do not limit the scope of the invention.

Aspects of this disclosure utilize different filtered-orthogonalfrequency division multiplexing (f-OFDM) frame formats to achieve thespectrum flexibility needed to support diverse traffic types innext-generation wireless networks. F-OFDM waveforms are generated byapplying a pulse shaping digital filter to an orthogonal frequencydivision multiplexed (OFDM) signal. Embodiments of this disclosure usedifferent frame formats to carry different traffic types as well as toadapt to characteristics of the channel, transmitter, receiver, orserving cell. The different frame formats utilize different sub-carrier(SC) spacings and/or cyclic prefix (CP) lengths. In some embodiments,the different frame formats also utilize different symbol durationsand/or transmission time interval (TTI) lengths. As referred to herein,the terms “frame format” and “frame structure configuration” are usedinterchangeably.

As mentioned above, using different frame formats to communicate trafficmay provide significant spectrum flexibility, as using differentcombinations of CP lengths, sub-carrier spacings, symbol durations, andTTI lengths has performance ramifications, e.g., latency, spectralefficiency, etc. In some embodiments, f-OFDM signals are assigned todifferent frame formats. The assignment may be based on any criteria,e.g., a characteristic of data carried in the respective f-OFDM signals,a characteristic of a wireless channel over which the f-OFDM signal istransmitted, a characteristic of a transmitter assigned to transmit thef-OFDM signal, a characteristic of a receiver assigned to receive thef-OFDM signal, etc. The assignment of frame formats to f-OFDM signalsmay be achieved in a variety of ways. In some embodiments, the frameformats are mapped to network resources, and the f-OFDM signals aretransmitted in the network resource based on that mapping to achieve theappropriate frame format assignment. In one example, different frameformats are mapped to different frequency sub-bands, and the f-OFDMsignals are assigned to whichever frequency sub-band is mapped to theappropriate frame format. In another example, different frame formatsare mapped to different time periods, and the f-OFDM signals areassigned to whichever time period has the appropriate frame format.Frame formats having different parameters may be in the same frequencysub-band or different frequency sub-bands. In other embodiments, theframe formats may be directly assigned to the f-OFDM signals independentof resource scheduling. In such embodiments, the assigned frame formatmay be used to transmit the f-OFDM signal over whichever resources areassigned to carry the f-OFDM signal. This may achieve greater networkflexibility, while potentially having higher overhead requirements byvirtue of having to persistently coordinate which frame formats arebeing applied to which network resources. These and other aspects aredescribed in further detail below.

FIG. 1 illustrates a network 100 for communicating data. The network 100includes an access point (AP) 110 having a coverage area 101, aplurality of mobile devices 120, and a backhaul network 130. The AP 110may be any component capable of providing wireless access by, amongother things, establishing uplink (dashed line) and/or downlink (dottedline) connections with the mobile devices 120, such as a base station,an evolved Node B (eNB), a femtocell, and other wirelessly enableddevices. The mobile devices 120 may be any component capable ofestablishing a wireless connection with the AP 110, such as a mobilestation (STA), a user equipment (UE), or other wirelessly enableddevices. The backhaul network 130 may be any component or collection ofcomponents that allow data to be exchanged between the AP 110 and aremote end. In some embodiments, there may be multiple such networks,and/or the network may comprise various other wireless devices, such asrelays, low power nodes, etc.

FIG. 2 illustrates a diagram of an embodiment filtered-orthogonalfrequency division multiplexing (f-OFDM) configuration 200. As shown,the f-OFDM configuration 200 comprises frequency sub-bands 210, 220,230, 240 over which different frame formats 201-204 are transmitted.Each of the different frame formats 201-204 has a different combinationof frame parameters, e.g., CP-lengths, SC spacing, symbol duration, TTIlength, etc. In some embodiments, different frame formats are assignedto different frequency sub-bands. In this example, the sub-band 210 isassigned the frame format 201, while the sub-band 220 is assigned theframe format 202. In other embodiments, different frame formats areassigned to be communicated at different time periods in the samefrequency sub-band. In this example, the frame formats 201, 202 areassigned in a time division multiplexed (TDM) fashion. While analternating pattern of two frame formats (i.e., the frame formats 201,202) are depicted as being communicated over the sub-band 230, it shouldbe appreciated that any pattern of frame formats, and any number ofdifferent frame formats, can be assigned to a frequency sub-band. Inother embodiments, different frame formats may be communicated overdifferent sub-carriers of the same frequency sub-band. In this example,the frame formats 203, 204 are communicated over different sub-carriersof the frequency sub-band 240. The bandwidths of the frequency sub-bands210, 220, 230 and 240 can be changed over time. Other examples are alsopossible.

In some embodiments, frame formats can be assigned to f-OFDM signalscommunicated over one or more frequency sub-bands. FIG. 3 illustrates adiagram of another embodiment f-OFDM configuration 300. As shown, thef-OFDM configuration 300 comprises frequency sub-bands 310, 320, 330over which different frame formats 301-309 are communicated. Each of thedifferent frame formats 301-309 has a different combination of frameparameters, e.g., CP-lengths, SC spacings, symbol durations, TTIlengths, etc. In this example, the frequency sub-band 320 is assigned adefault frame format 305. The frame format 305 may have a standard setof frame parameters (e.g., CP-length, SC-spacing, symbol duration, etc.)that is known by mobile devices. The default frame format 305 can betransmitted continuously in time or it can be transmitted periodically(e.g. “Config 1” in FIG. 7). This may allow mobile devices entering thewireless network to receive signals in the frequency sub-band 320. Thefrequency sub-band 320 may be used to assign frame formats to thefrequency sub-band 310, as well as to assign frame formats to thefrequency sub-band 330. Notably, dynamically assigning frame formats tothe frequency sub-band 310 may allow a different frame format to beassigned to each f-OFDM signal on a frame-by-frame basis. In thisexample, the frame format 301 is assigned to a first f-OFDM signalcommunicated over the frequency sub-band 310, the frame format 302 isassigned to a second f-OFDM signal communicated over the frequencysub-band 310, the frame format 303 is assigned to a third f-OFDM signalcommunicated over the frequency sub-band 310, and the frame format 304is assigned to a forth f-OFDM signal communicated over the frequencysub-band 310. The bandwidths of frequency sub-bands 310, 320 and 330 canbe changed over time.

Semi-static configuration of frame formats in the frequency sub-band 330may allow different frame formats to be assigned to differentsemi-static allocation periods 331, 332. Semi-static configuration offrame formats may generate less overhead than dynamic configuration offrame formats. In this example, the frame format 302 is assigned to thesemi-static allocation period 331, and the frame format 309 is assignedto the semi-static allocation period 332.

FIG. 4 illustrates an embodiment method 400 for transmitting f-OFDMsignals having different frame formats, as may be performed by atransmitter. As shown, the method 400 begins at step 410, where thetransmitter transmits a first f-OFDM signal. Next, the method 400proceeds to step 420, where the transmitter transmits a second f-OFDMsignal. Symbols carried by the second f-OFDM signal have a differentCP-length than symbols carried by the first f-OFDM signal. Additionally,the second f-OFDM signal is communicated over sub-carriers having adifferent sub-carrier spacing than the first f-OFDM signal.

In some embodiments, different frame formats are assigned to differentf-OFDM signals. FIG. 5 illustrates another embodiment method 500 fortransmitting f-OFDM signals having different frame formats, as may beperformed by a transmitter. As shown, the method 500 begins at step 510,where the transmitter configures different frame formats to f-OFDMsubbands based on one or more criteria. Next, the method 500 proceeds tostep 520, where the transmitter transmits the f-OFDM signals inaccordance with the assigned frame formats.

The criteria used to make the frame format assignments may includevarious characteristics associated with the signal transmission. In oneexample, the criteria includes a characteristic of data carried in therespective f-OFDM signals, e.g., a latency requirement, a delaytolerance requirement, a traffic type, a service type, etc. In anotherexample, the criteria includes a characteristic of a wireless channelover which the f-OFDM signals are transmitted, e.g., multipath delaycharacteristic, a path loss, etc. In yet another example, the criteriaincludes a characteristic of the transmitter, e.g., a serving regionsize, etc. In yet another example, the criteria includes acharacteristic of the receiver assigned to receive the f-OFDM signal,e.g., a mobility speed of the receiver. The criteria may also include acombination of the above-mentioned characteristics.

In some embodiments, frames having different frame formats are receivedby a single receiver. FIG. 6 illustrates an embodiment method 600 forreceiving f-OFDM signals having different frame formats, as may beperformed by a receiver. As shown, the method 600 begins at step 610,where the receiver receives a first f-OFDM signal. Next, the method 600proceeds to step 620, where the receiver receives a second f-OFDM signalcarrying symbols having a different CP-length than symbols carried bythe first f-OFDM signal, as well as being communicated over sub-carriershaving a different sub-carrier spacing than the first f-OFDM signal.

Current adaptive TTI design for 5G only works with the same subcarrierspacing and symbol duration. Various embodiments relate to framestructure design in the 5G air interface are provided. Embodimentsprovide a system and method for an adaptive and flexible frame structure(e.g., subcarrier spacing, symbol prefix/suffix, TTI length, etc.) inthe same system bandwidth to work in filtered OFDM. Embodiments providean adaptive frame structure (in which TTI is only one element, andsubcarrier spacing and symbol prefix/suffix duration are others) thatcan coexist when combined with filtered OFDM in the same systembandwidth. Embodiments provide a more flexible solution to meet thediverse environment and traffic types of 5G systems due to the abilityto accommodate different frame structure parameters, while at the sametime enabling mobile devices to access such system easily.

FIG. 7 illustrates examples of frame structure configurations, whichinclude subcarrier spacing, total symbol duration, symbol prefix/suffixconfiguration, and TTI length. As illustrated in FIG. 7, Configuration 1is a default configuration. Configuration 2 is a configuration for lowlatency machine-type communication (MTC), and configuration 3 is aconfiguration for delay tolerant MTC. Configuration 4 is for highmobility, and configuration 5 is for broadcast service. This isapplicable for both downlink and uplink.

In the intra-f-OFDM sub-band, the frame structure configurations withthe same subcarrier spacing and total symbol duration can coexist. Theinter-f-OFDM sub-band includes configurations with different subcarrierspacing and total symbol duration. The default frame structure occurs inpredefined time-frequency resources within a default f-OFDM sub-band.This occurs at predefined periods, not necessarily all of the time. Itfacilitates initial access by mobile device, and may be mandatory fordownlink (DL), but optional for uplink (UL). The default frame structurecan be a backward compatible frame structure configuration (e.g.,long-term evolution (LTE)) or a 5G default frame structureconfiguration. This depends on, for example, carrier frequencies.

A mechanism for adaptive frame structure with f-OFDM according toembodiments is described as follows. First, a default frame structureparameter set (configuration) is defined (e.g., default subcarrierspacing, total symbol duration, TTI length, symbol overhead such asprefix/suffix length, etc.). Next, additional frame structure parameterssets (configurations) different from the default frame structureparameter set are defined. In an embodiment, the different f-OFDMsub-band frame structure has at least a different SC spacing and totalsymbol duration.

Next, the default frame structure is transmitted in predefinedtime-frequency resources within a default f-OFDM sub-band. This is knownat both the network and the mobile device (e.g., located in thebandwidth (BW) around the carrier frequency for DL). The default f-OFDMsub-band is at least the BW of the time-frequency resources occupied bythe default frame structure. The default frame structure can be used forcarrying any type of traffic. FIG. 8 illustrates a default f-OFDMsub-band according to an embodiment. Finally, additional framestructures in other f-OFDM sub-bands are configured on demand.

Default frame structure parameter set embodiments include a default 5Gframe structure parameter set that is different from that of LTE. An LTEframe structure parameter set may include, e.g., SC (sub-carrierspacing)=15 kHz, TTI=1 ms, etc. Additional frame structure parameter setembodiments including frame structures for high speed and low speed,frame structures for a dispersive channel (e.g., outdoor) and a lessdispersive channel (e.g., indoor), frame structures for differentcarrier frequencies, and frame structures for different trafficcharacteristics (e.g., latency). Table 1 lists the types of parametersthat are well suited for different traffic/receivers. Table 2 listsexample frame format parameters for a 7.5 kilohertz (KHz) sub-carrierspacing. Table 3 lists example frame format parameters for a 15kilohertz (KHz) sub-carrier spacing. Table 4 lists example frame formatparameters for a 30 kilohertz (KHz) sub-carrier spacing. Table 5 listsexample frame format parameters for a 30 kilohertz (KHz) sub-carrierspacing. Table 6 illustrates example f-OFDM frame parameters selectedfrom Table 1 to 5 for various configurations. The parameters may supportsmooth scalability of LTE in terms of subcarrier spacing (e.g., 7.5, 15,30, 60 kHz). Embodiments include backward compatibility with the LTEbasic time unit (or sampling frequency of 30.72 MHz). Variousembodiments provide for narrow subcarrier spacing of 7.5 KHz alongconsidering for device-to-device (D2D) or MTC. Various embodiments alsosupport three types of CP for different environments, e.g., outdoor andindoor, large and small cells, e.g., mini CP (1˜2 us), normal CP (˜5 us)and extended CP (>5 us). Embodiments provide for reduced and varying CPoverhead options, e.g., 1%˜10%, and short and long TTIs, e.g., able toform different frame sizes of, e.g., 0.15 ms, 1 ms, 5 ms, etc.

TABLE 1 Configuration SC-Spacing Symbol Dur. CP-Prefix TTI MTC Low smalllong long short Latency MTC Delay small long long medium Tolerant HighMobility large short medium medium Broadcast Services medium medium longmedium

TABLE 2 Subcarrier spacing (KHz) 7.5 7.5 7.5 7.5 Useful duration T_u(us) 133.333 133.333 133.333 133.333 CP length (us) 16.667 9.54/9.445.57/5.18 1.82/1.76 CP length in Ts (=32.55 ns) 512 293/290 171/15956/54 # of symbols per TTI 1 6/1 35/1  25/12 TTI (ms) 0.150 1 5 5 CPoverhead 11.11% 6.67% 4.00% 1.33%

TABLE 3 Subcarrier spacing (KHz) 15 15 15 Useful duration T_u (us)66.667 66.667 66.667 CP length (us) 8.333 5.2/4.7 2.31/2.28 CP length inTs (=32.55 ns) 256 160/144 71/70 # of symbols per TTI 2 1/6 18/11 TTI(ms) 0.150 0.5 2 CP overhead 11.11% 6.67% 3.33%

TABLE 4 Subcarrier spacing (KHz) 30 30 30 30 Useful duration T_u (us)33.333 33.333 33.333 33.333 CP length (us) 4.167 2.4/2.38 3.71/3.651.17/1.14 CP length in Ts (=32.55 ns) 128 74/73 114/112 36/35 # ofsymbols per TTI 4 1/6 8/1  9/20 TTI (ms) 0.150 0.250 0.333 1 CP overhead11.11% 6.67% 10.00% 3.33%

TABLE 5 Subcarrier spacing (KHz) 60 60 60 60 Useful duration T_u (us)16.667 16.667 16.667 16.667 CP length (us)  1.2/1.17 2.083 1.53/1.370.88/0.85 CP length in Ts (=32.55 ns) 37/36 64 47/42 27/26 # of symbolsper TTI 4/3 8 10/1  18/1  TTI (ms) 0.125 0.150 0.200 0.333 CP overhead6.67% 11.11% 8.33% 5.00%

TABLE 6 Symbol Dur. Configuration SC-Spacing (μs) CP-Prefix (μs) TTI(ms) MTC Low 7.5 133.333 16.667 0.15 Latency MTC Delay 7.5 133.33316.667 1.5 Tolerant High Mobility 30 33.333 3.71/3.65 0.333 LTE Comp. 1566.7  5.2/4.69 1

FIG. 9 is a diagram illustrating an embodiment f-OFDM configuration forsupporting adaptive frame formats. In this embodiment, the 4 frameformats listed in Table 6 are communicated in 3 f-OFDM subbands of a 20MHz spectrum. With the use of f-OFDM, the OFDM total symbol durations(cyclic prefix+useful symbol duration) corresponding to different framestructure configurations do not need to be aligned as shown in thefigure. That is, non-orthogonal sets of parameters can co-exist. Forexample, the 30 kHz (“High mobility”) configuration has an OFDM totalsymbol duration of around 37 μs whereas the 15 kHz (“LTE compatible”)configuration has an OFDM total symbol duration of around 71 μs.

F-OFDM parameters can be communicated in a control channel of a defaultf-OFDM frame. FIG. 10 illustrates a flowchart of an embodiment method1000 for configuring a downlink f-OFDM frame, as may be performed by atransmitter. As shown, the method 1000 begins at step 1010, where thetransmitter determines f-OFDM parameters for f-OFDM signals. Thereafter,the method 1000 proceeds to step 1020, where the transmitter transmitsthe f-OFDM signals in accordance with the f-OFDM parameters. The DLf-OFDM parameters may include sub-band information and frame parameters.The sub-band information may include indexes of sub-bands, offsets froma reference value, or any other information associated with a sub-band.The frame parameters may identify a subcarrier spacing, a symbolduration, an overhead configuration (e.g., cyclic prefix (CP) length,etc.), a transmission time interval (TTI) duration, or any otherparameter corresponding to the structure of an f-OFDM frame. The frameparameters may include indexes of a parameter set, indexes of individualparameters, or any other index, parameter, or value associated with aframe structure.

F-OFDM parameters can be communicated via higher-layer signaling. FIG.11 illustrates a flowchart of an embodiment method 1100 for modifyingdownlink (DL) f-OFDM parameters, as may be performed by a transmitter.As shown, the method 1100 begins at step 1110, where the transmittermodifies DL f-OFDM parameters for DL f-OFDM signals based on criteria.The criteria may include a characteristic of data carried by the DLf-OFDM signals, a characteristic of a channel, a characteristic of thetransmitter, or a characteristic of a receiver assigned to receive theDL f-OFDM signals (or a combination thereof). Thereafter, the method1100 proceeds to step 1120, where the transmitter transmits the DLf-OFDM parameters via higher-layer signaling, e.g., radio resourcecontrol (RRC) signaling, etc. Finally, the method 1100 proceeds to step1130, where the transmitter transmits the DL f-OFDM signals inaccordance with the DL f-OFDM parameters.

F-OFDM parameters can be communicated via a default f-OFDM frame. FIG.12 illustrates a flowchart of an embodiment method 1200 for modifying DLf-OFDM parameters, as may be performed by a transmitter. As shown, themethod 1200 begins at step 1210, where the transmitter modifies DLf-OFDM parameters for DL f-OFDM signals based on criteria. Thereafter,the method 1200 proceeds to step 1220, where the transmitter transmitsthe modified DL f-OFDM parameters via a default DL f-OFDM frame. Thef-OFDM parameters may be communicated in a control channel of thedefault DL f-OFDM frame. Finally, the method 1200 proceeds to step 1230,where the transmitter transmits the DL f-OFDM signals in accordance withthe DL f-OFDM parameters.

F-OFDM parameters can be communicated via a previously modified f-OFDMframe. FIG. 13 illustrates a flowchart of an embodiment method 1300 formodifying DL f-OFDM parameters, as may be performed by a transmitter. Asshown, the method 1300 begins at step 1310, where the transmittermodifies DL f-OFDM parameters for DL f-OFDM signals based on criteria.Thereafter, the method 1300 proceeds to step 1320, where the transmittertransmits the modified DL f-OFDM parameters via a previously modifiedf-OFDM frame. The DL f-OFDM parameters may be communicated in a controlchannel of the previously modified DL f-OFDM frame. Finally, the method1300 proceeds to step 1330, where the transmitter transmits the DLf-OFDM signals in accordance with the newly modified DL f-OFDMparameters. This method may be particularly useful for modificationsthat affect mobile devices using other frame structures in other f-OFDMsub-bands, e.g., modifying other f-OFDM sub-band sizes, SC spacing,total symbol duration, and overhead duration.

It is also possible to configure uplink (UL) f-OFDM frames. FIG. 14illustrates a flowchart of an embodiment method 1400 for configuring anuplink f-OFDM frame, as may be performed by a base station. As shown,the method 1400 begins at step 1410, where the base station determinesUL f-OFDM parameters for f-OFDM signals. Thereafter, the method 1400proceeds to step 1420, where the base station transmits the UL f-OFDMparameters to a mobile device. The UL f-OFDM parameters may becommunicated via higher layer signaling or in a control channel of adownlink f-OFDM frame (e.g., default, modified, or otherwise). Finally,the method 1400 proceeds to step 1430, where the base station receivesthe f-OFDM signals in accordance with the UL f-OFDM parameters.

FIG. 15 illustrates a flowchart of an embodiment method 1500 fortransmitting an UL f-OFDM frame, as may be performed by a mobile device.As shown, the method 1500 begins at step 1510, where the mobile devicereceives UL f-OFDM parameters from a base station. The UL f-OFDMparameters may be communicated via higher layer signaling or in acontrol channel of a downlink f-OFDM frame (e.g., default, modified, orotherwise). Thereafter, the method 1500 proceeds to step 1520, where themobile device transmits UL f-OFDM signals in accordance with the ULf-OFDM parameters. If UL f-OFDM parameters are not pre-defined (e.g.,there is no default UL f-OFDM frame), then a mobile device may obtainframe structure information from DL related signaling on initial access.If UL f-OFDM parameters are pre-defined, then a mobile device maytransmit on the UL in the default frame structure without waiting forthe UL f-OFDM parameters to be signaled by the base station. Thus,pre-configure the initial frame structure and f-OFDM sub-band may reduceoverhead.

FIGS. 16-19 illustrate embodiment f-OFDM configurations. In thosefigures, transmission time interval parameters are designated as “TTI,”sub-carrier spacing parameters are designated as “SC,” total symbolduration parameters are designated as “T,” and symbol overhead due tocyclic prefix, cyclic suffix or zero tails is designated as “O.” FIG. 16illustrates a different frame structure on different f-OFDM sub-bands,and a same frame structure within a f-OFDM sub-band, according to anembodiment. FIG. 17 illustrates a different frame structure on differentf-OFDM sub-bands, and different TTI lengths within a f-OFDM sub-band,according to an embodiment. The sub-carrier spacing, total symbolduration and symbol overhead, however, are the same within a f-OFDMsub-band. FIG. 18 illustrates different frame structures on differentf-OFDM sub-bands, and different TTI lengths and symbol overhead within af-OFDM sub-band, according to an embodiment. For example, this examplemay use zero-tail DFT-s-OFDM or adjustable zero-tail DFT-s-OFDM toprovide the different symbol overhead. FIG. 19 illustrates a backwardcompatible extension (LTE frame structures), according to an embodiment.This may include normal and extended CP frame structures on differentf-OFDM sub-bands occurring simultaneously.

FIG. 20 illustrates an example of an intra-f-OFDM adaptive TTIconfiguration, according to an embodiment. In this embodiment, a set ofmappings (patterns) of logical TTI resources to physical TTI resourcesin a time duration (e.g., a radio frame of 10 ms) is defined. Mappingcan be changed from frame to fame (e.g., by cycling through a predefinedset of mappings or by signaling. The mapping can be of localized ordistributed types. With localized TTI mapping, a TTI length occupiesphysical resources in the same bandwidth for the duration of a frame.With distributed TTI mapping, different TTI lengths can hop across theentire bandwidth as shown in FIG. 20. This allows for the exploitationof frequency diversity.

In accordance with an embodiment, a method for transmitting signals in awireless network is provided. In this example, the method includestransmitting a first filtered-orthogonal frequency division multiplexing(f-OFDM) signal, and transmitting a second f-OFDM signal. The firstf-OFDM signal and the second f-OFDM signal are communicated inaccordance with different sub-carrier spacings than one another. Thefirst f-OFDM signal and the second f-OFDM signal may carry symbolshaving different cyclic prefix (CP) lengths than one another. The firstf-OFDM signal and the second f-OFDM signal may be transmitted over thesame frequency sub-band during different transmission time intervals(TTIs). The first f-OFDM signal and the second f-OFDM signal may betransmitted over different frequency sub-bands during the same timeperiod.

The method may further comprise assigning a first frame format to thefirst f-OFDM signal and a second frame format to the second f-OFDMsignal. The first frame format may require a different CP length and adifferent sub-carrier spacing than the second frame format. In anembodiment, assigning the first frame format to the first f-OFDM signalcomprises selecting the first frame format based on a characteristic ofdata to be carried by the first f-OFDM signal. The characteristic of thedata to be carried by the first f-OFDM signal may comprise a latencyrequirement, a delay tolerance requirement, a traffic type, a servicetype, or a combination thereof. In another embodiment, assigning thefirst frame format to the first f-OFDM signal comprises selecting thefirst frame format based on a characteristic of a wireless channel overwhich the first f-OFDM signal is to be transmitted. The characteristicof the wireless channel comprises a multipath delay of the wirelesschannel. In yet another embodiment, assigning the first frame format tothe first f-OFDM signal comprises selecting the first frame format basedon a serving region size of the transmitter. In yet another embodiment,assigning the first frame format comprises selecting the first frameformat based on a characteristic of a receiver associated with the firstf-OFDM signal. The characteristic of the receiver associated with thefirst f-OFDM signal may comprise a mobility speed of the receiver.

In an embodiment, the first f-OFDM signal and the second f-OFDM signalare received by a receiver. The first f-OFDM signal may be communicatedin accordance with a default frame format that is known by the receiver.The first f-OFDM signal may indicate that the second f-OFDM signal willbe communicated in accordance with a frame format that is different thanthe default frame format.

In accordance with another embodiment, a method for receiving signals ina wireless network is provided. In this example, the method includesreceiving a first filtered-orthogonal frequency division multiplexing(f-OFDM) signal, and receiving a second f-OFDM signal. The first f-OFDMsignal and the second f-OFDM signal are communicated in accordance withdifferent sub-carrier spacings than one another. The first f-OFDM signaland the second f-OFDM signal may carry symbols having different cyclicprefix (CP) lengths than one another. The first f-OFDM signal and thesecond f-OFDM signal may be received over the same frequency sub-bandduring different transmission time intervals (TTIs). The first f-OFDMsignal and the second f-OFDM signal may be received over differentfrequency sub-bands during the same time period. The first f-OFDM may becommunicated in accordance with a default frame format that is known bythe receiver, and the first f-OFDM signal may indicate that the secondf-OFDM signal will be communicated in accordance with a frame formatthat is different than the default frame format.

FIG. 21 illustrates a block diagram of an embodiment processing system2100 for performing methods described herein, which may be installed ina host device. As shown, the processing system 2100 includes a processor2104, a memory 2106, and interfaces 2110-2114, which may (or may not) bearranged as shown in FIG. 21. The processor 2104 may be any component orcollection of components adapted to perform computations and/or otherprocessing related tasks, and the memory 2106 may be any component orcollection of components adapted to store programming and/orinstructions for execution by the processor 1504. In an embodiment, thememory 2106 includes a non-transitory computer readable medium. Theinterfaces 2110, 2112, 2114 may be any component or collection ofcomponents that allow the processing system 2100 to communicate withother devices/components and/or a user. For example, one or more of theinterfaces 2110, 2112, 2114 may be adapted to communicate data, control,or management messages from the processor 2104 to applications installedon the host device and/or a remote device. As another example, one ormore of the interfaces 2110, 2112, 2114 may be adapted to allow a useror user device (e.g., personal computer (PC), etc.) tointeract/communicate with the processing system 2100. The processingsystem 2100 may include additional components not depicted in FIG. 21,such as long term storage (e.g., non-volatile memory, etc.).

In some embodiments, the processing system 2100 is included in a networkdevice that is accessing, or part otherwise of, a telecommunicationsnetwork. In one example, the processing system 2100 is in a network-sidedevice in a wireless or wireline telecommunications network, such as abase station, a relay station, a scheduler, a controller, a gateway, arouter, an applications server, or any other device in thetelecommunications network. In other embodiments, the processing system2100 is in a user-side mobile device accessing a wireless or wirelinetelecommunications network, such as a mobile station, a user equipment(UE), a personal computer (PC), a tablet, a wearable communicationsdevice (e.g., a smartwatch, etc.), or any other device adapted to accessa telecommunications network.

In some embodiments, one or more of the interfaces 2110, 2112, 2114connects the processing system 2100 to a transceiver adapted to transmitand receive signaling over the telecommunications network. FIG. 22illustrates a block diagram of a transceiver 2200 adapted to transmitand receive signaling over a telecommunications network. The transceiver2200 may be installed in a host device. As shown, the transceiver 2200comprises a network-side interface 2202, a coupler 2204, a transmitter2206, a receiver 2208, a signal processor 2210, and a device-sideinterface 2212. The network-side interface 2202 may include anycomponent or collection of components adapted to transmit or receivesignaling over a wireless or wireline telecommunications network. Thecoupler 2204 may include any component or collection of componentsadapted to facilitate bi-directional communication over the network-sideinterface 2202. The transmitter 2206 may include any component orcollection of components (e.g., up-converter, power amplifier, etc.)adapted to convert a baseband signal into a modulated carrier signalsuitable for transmission over the network-side interface 2202. Thereceiver 2208 may include any component or collection of components(e.g., down-converter, low noise amplifier, etc.) adapted to convert acarrier signal received over the network-side interface 2202 into abaseband signal. The signal processor 2210 may include any component orcollection of components adapted to convert a baseband signal into adata signal suitable for communication over the device-side interface(s)2212, or vice-versa. The device-side interface(s) 2212 may include anycomponent or collection of components adapted to communicatedata-signals between the signal processor 2210 and components within thehost device (e.g., the processing system 2100, local area network (LAN)ports, etc.).

The transceiver 2200 may transmit and receive signaling over any type ofcommunications medium. In some embodiments, the transceiver 2200transmits and receives signaling over a wireless medium. For example,the transceiver 2200 may be a wireless transceiver adapted tocommunicate in accordance with a wireless telecommunications protocol,such as a cellular protocol (e.g., long-term evolution (LTE), etc.), awireless local area network (WLAN) protocol (e.g., Wi-Fi, etc.), or anyother type of wireless protocol (e.g., Bluetooth, near fieldcommunication (NFC), etc.). In such embodiments, the network-sideinterface 2202 comprises one or more antenna/radiating elements. Forexample, the network-side interface 2202 may include a single antenna,multiple separate antennas, or a multi-antenna array configured formulti-layer communication, e.g., single input multiple output (SIMO),multiple input single output (MISO), multiple input multiple output(MIMO), etc. In other embodiments, the transceiver 2200 transmits andreceives signaling over a wireline medium, e.g., twisted-pair cable,coaxial cable, optical fiber, etc. Specific processing systems and/ortransceivers may utilize all of the components shown, or only a subsetof the components, and levels of integration may vary from device todevice.

In an embodiment, a method for transmitting signals in a wirelessnetwork is provided. In this embodiment, the method includescommunicating, by a wirelessly-enabled device, a first orthogonalfrequency division multiplexing (OFDM) signal using a first framestructure configuration; and communicating, by the wirelessly-enableddevice, a second OFDM signal using a second frame structureconfiguration. The first OFDM signal at least partially overlapping thesecond OFDM signal in the time-domain. The first frame structureconfiguration is at least partially misaligned with the second framestructure configuration in the time domain such that at least some pairsof overlapping slots in the first and second frame structureconfigurations have different starting or ending slot locations. In oneexample, the first OFDM signal and the second OFDM signal carry symbolshave different cyclic prefix (CP) lengths than one another. In the sameexample or another example, the first OFDM signal and the second OFDMsignal are transmitted over different frequency sub-bands. In any one ofthe preceding examples, or in another example, starting locations of allslots in the first frame structure configuration are offset fromstarting locations of all slots in the second frame structure. In suchan example, slots in the first frame structure configuration may havethe same periodic duration as slots in the second frame structureconfiguration. Alternatively, in such an example, slots in the firstframe structure configuration have a different periodic duration asslots in the second frame structure configuration. In any one of thepreceding examples, or in another example, the wirelessly-enabled deviceis a mobile device or an access point. An apparatus and computer programproduct for performing this method are also provided.

In accordance with an embodiment, a method for transmitting signals in awireless network is provided. In this example, the method includestransmitting, by a transmitter, a first transmission in a defaultsub-band with default orthogonal frequency divisional multiplexing(OFDM) parameters to a first user equipment (UE) when the UE initiallyaccesses a network, and transmitting, by the transmitter, higher-layersignaling to the first UE in the default sub-band. The higher-layersignaling indicates at least one first OFDM additional parameters andone second OFDM parameters. The first OFDM additional parametersincludes a first additional sub-band information and a first additionalframe structure parameters, and the second OFDM parameters includes asecond additional sub-band information and a second additional framestructure parameters. The first additional sub-band occupies a differentfrequency bandwidth partition than the second additional sub-band. Afirst sub-carrier spacing in the first additional frame structureparameters is different than a second sub-carrier spacing in the secondadditional frame structure parameters. The sub-carrier spacing in thedefault frame structure parameters comprises 15 kilohertz (kHz) and 30kHz, and each of the first sub-carrier spacing and the secondsub-carrier spacing is one from a predefined sub-carrier spacing set of7.5 kHz, 15 kHz, 30 kHz, and 60 kHz. In one example, the bandwidth ofthe first additional sub band and the second additional sub band is 5MHz. In the same example, or in another example, each of the firstadditional sub-band information and the second additional sub-bandinformation comprises an index of a sub-band or an offset from areference value associating with each sub-band. In any one of the aboveexamples, or in another example, each of the first additional framestructure parameters and the second additional frame structureparameters further comprises cyclic prefix (CP) length and transmissiontime intervals (TTIs). In any one of the above examples, or in anotherexample, the first additional frame structure parameters and the secondadditional frame structure parameters includes an index for eachsub-carrier spacing. In any one of the above examples, or in anotherexample, before the step of transmitting the first transmission, themethod further comprises continuously transmitting, by the transmitter,the default frame structure parameters in time; or periodicallytransmitting, by the transmitter, the default frame structureparameters. In any one of the above examples, or in another example, aframe format (e.g., the frame format 302 from FIG. 3) is assigned to asemi-static allocation period (e.g., the semi-static allocation period331), and another frame format (e.g., the frame format 309) is assignedto another semi-static allocation period (e.g., the semi-staticallocation period 332). In any one of the above examples, or in anotherexample, the default sub-band is a default filtered-orthogonalfrequency-division multiplexing (f-OFDM) sub-band, and the additionalsub-band is an additional f-OFDM sub-band.

In accordance with another embodiment, a method for transmitting signalsin a wireless network is provided. In this example, the method includestransmitting, by a transmitter, a first transmission in a defaultsub-band with default orthogonal frequency divisional multiplexing(OFDM) parameters to a first user equipment (UE) when the UE initiallyaccesses a network, and transmitting, by the transmitter, higher-layersignaling to the first UE in the default sub-band. The higher-layersignaling indicates at least a first set of alternative OFDM parametersand a second set of alternative OFDM parameters, the first set ofalternative OFDM parameters including at least a first alternativesub-band, and a first alternative frame structure, and the second set ofalternative OFDM parameters including a second alternative sub-band anda second alternative frame structure, wherein the first alternativesub-band occupies a different frequency bandwidth partition than thesecond alternative sub-band. The default frame structure parameterscomprises at least one of a 15 kilohertz (kHz) subcarrier spacing and 30kHz subcarrier spacing. The first frame structure and the second framestructure include one of a 7.5 kHz sub-carrier spacing, a 15 kHzsub-carrier spacing, a 30 kHz sub-carrier spacing, and a 60 kHzsub-carrier spacing. The first frame structure has a differentsub-carrier spacing than the second frame structure. In one example,each of the first sub-band and the second—sub-band have a 5 megahertz(MHz) bandwidth. In the same example, or in another example, each of thefirst sub-band and the second sub-band are associated with an index ofsub-band or offset from a reference value associating with eachsub-band, the index or the offset being indicating by the higher-layersignaling. In any one of the above examples, or in another example, eachof the first frame structure and the second frame structure comprisescyclic prefix (CP) length and transmission time intervals (TTIs). In anyone of the above examples, or in another example, the first plurality ofOFDM parameters includes a first index for a first sub-carrier spacingof the first frame structure, and wherein the second plurality of OFDMparameters includes a second index for a second sub-carrier spacing ofthe second frame structure. In such an example, the first sub-carrierspacing of the first frame structure may be different than the secondsub-carrier spacing of the second frame structure. In any one of theabove examples, or in another example, before the step of transmittingthe first transmission, the method further comprises continuouslytransmitting, by the transmitter, the default frame structure parametersin time. In any one of the above examples, or in another example, themethod further comprises periodically transmitting, by the transmitter,the default frame structure parameters. In any one of the aboveexamples, or in another example, the default sub-band is a defaultfiltered-orthogonal frequency-division multiplexing (f-OFDM) sub-band,and the first alternative sub-band is an alternative f-OFDM sub-band.

While this invention has been described with reference to illustrativeembodiments, this description is not intended to be construed in alimiting sense. Various modifications and combinations of theillustrative embodiments, as well as other embodiments of the invention,will be apparent to persons skilled in the art upon reference to thedescription. It is therefore intended that the appended claims encompassany such modifications or embodiments.

What is claimed is:
 1. A method for transmitting signals in a wirelessnetwork, the method comprising: transmitting, by a transmitter, to auser equipment (UE), a downlink related signaling indicating defaultframe structure parameters when the UE initially accesses a network; andtransmitting, by the transmitter, to the UE, a first transmission in adefault sub-band with the default frame structure parameters;transmitting, by the transmitter, to the UE, a higher-layer signaling toindicate additional frame structure parameters and an additionalsub-band; and transmitting, by the transmitter, to the UE, a secondtransmission in the additional sub-band with the additional framestructure parameters, wherein the default sub-band and the additionalsub-band are in a same system bandwidth, the default frame structureparameters comprise a first sub-carrier spacing, the additional framestructure parameters comprise a second sub-carrier spacing, and wherein:the first sub-carrier spacing and the second sub-carrier spacing bothare 15 kilohertz (kHz); the first sub-carrier spacing and the secondsub-carrier spacing both are 30 kHz; or the first sub-carrier spacing is15 kHz, and the second sub-carrier spacing is 30 kHz.
 2. The method ofclaim 1, wherein a bandwidth of the additional sub-band is 5 megahertz(MHz).
 3. The method of claim 1, wherein the higher-layer signalingcomprises an index of the additional sub-band or an offset from areference value associated with the additional sub-band.
 4. The methodof claim 1, wherein the higher-layer signaling includes an index for thesecond sub-carrier spacing.
 5. The method of claim 1, before the step oftransmitting the first transmission, further comprising: continuously orperiodically transmitting, by the transmitter, a set of default framestructure parameters in time.
 6. The method of claim 1, wherein theadditional frame structure parameters correspond to a first frame formatassigned to a first semi-static allocation period.
 7. The method ofclaim 1, wherein the default sub-band is a default filtered-orthogonalfrequency-division multiplexing (f-OFDM) sub-band and the additionalsub-band is an additional f-OFDM sub-band.
 8. The method of claim 1,wherein the default sub-band and the additional sub-band arenon-overlapping sub-bands, and wherein the second sub-carrier spacing isdifferent from the first sub-carrier spacing.
 9. The method of claim 1,wherein the additional frame structure parameters include a firsttransmission time interval (TTI), and wherein the higher-layer signalingcomprises an index or value for the first TTI.
 10. The method of claim1, wherein the default sub-band and the additional sub-band occupyeither a same frequency partition within different transmission timeintervals (TTIs) or different frequency partitions within a same TTI.11. A transmitter comprising: a processor; and a non-transitory computerreadable storage medium storing programming for execution by theprocessor, the programming including instructions to: transmit, to auser equipment (UE), a downlink related signaling indicating defaultframe structure parameters when the UE initially accesses a network; andtransmit, to the UE, a first transmission in a default sub-band with thedefault frame structure parameters; transmit, to the UE, a higher-layersignaling to indicate additional frame structure parameters and anadditional sub-band; and transmitting, by the transmitter, to the UE, asecond transmission in the additional sub-band with the additional framestructure parameters, wherein the default sub-band and the additionalsub-band are in a same system bandwidth, the default frame structureparameters comprise a first sub-carrier spacing, the additional framestructure parameters comprise a second sub-carrier spacing, and wherein:the first sub-carrier spacing and the second sub-carrier spacing bothare 15 kilohertz (kHz); the first sub-carrier spacing and the secondsub-carrier spacing both are 30 kHz; or the first sub-carrier spacing is15 kHz, and the second sub-carrier spacing is 30 kHz.
 12. Thetransmitter of claim 11, wherein a bandwidth of the additional sub-bandis 5 megahertz (MHz).
 13. The transmitter of claim 11, wherein thehigher-layer signaling comprises an index of the additional sub-band oran offset from a reference value associated with the additionalsub-band.
 14. The transmitter of claim 11, wherein the higher-layersignaling includes an index for the second sub-carrier spacing.
 15. Thetransmitter of claim 11, wherein the programming further includesinstructions to: continuously or periodically transmit a set of defaultframe structure parameters in time.
 16. The transmitter of claim 11,wherein the additional frame structure parameters correspond to a firstframe format assigned to a first semi-static allocation period.
 17. Thetransmitter of claim 11, wherein the default sub-band is a defaultfiltered-orthogonal frequency-division multiplexing (f-OFDM) sub-bandand the additional sub-band is an additional f-OFDM sub-band.
 18. Thetransmitter of claim 11, wherein the default sub-band and the additionalsub-band are non-overlapping sub-bands, and wherein the secondsub-carrier spacing is different from the first sub-carrier spacing. 19.The transmitter of claim 11, wherein the additional frame structureparameters include a first transmission time interval (TTI), and whereinthe higher-layer signaling comprises an index or value for the firstTTI.
 20. The transmitter of claim 11, wherein the default sub-band andthe additional sub-band occupy either a same frequency partition withindifferent transmission time intervals (TTIs) or different frequencypartitions within a same TTI.
 21. A method for receiving signals in awireless network, the method comprising: receiving, by a user equipment(UE), from a transmitter, a downlink related signaling indicatingdefault frame structure parameters when the UE initially accesses anetwork; receiving, by the UE, from the transmitter, a firsttransmission in a default sub-band with the default frame structureparameters; receiving, by the UE, from the transmitter, a higher-layersignaling to indicate additional frame structure parameters and anadditional sub-band; and receiving, by the UE, from the transmitter, asecond transmission in the additional sub-band with the additional framestructure parameters, wherein the default sub-band and the additionalsub-band are in a same system bandwidth, the default frame structureparameters comprise a first sub-carrier spacing, the additional framestructure parameters comprise a second sub-carrier spacing, and wherein:the first sub-carrier spacing and the second sub-carrier spacing bothare 15 kilohertz (kHz); the first sub-carrier spacing and the secondsub-carrier spacing both are 30 kHz; or the first sub-carrier spacing is15 kHz, and the second sub-carrier spacing is 30 kHz.
 22. The method ofclaim 21, wherein a bandwidth of the additional sub-band is 5 megahertz(MHz).
 23. The method of claim 21, wherein the higher-layer signalingcomprises an index of the additional sub-band or an offset from areference value associated with the additional sub-band.
 24. The methodof claim 21, wherein the higher-layer signaling includes an index forthe first sub-carrier spacing.
 25. The method of claim 21, wherein theadditional frame structure parameters correspond to a first frame formatassigned to a first semi-static allocation period.
 26. The method ofclaim 21, wherein the default sub-band is a default filtered-orthogonalfrequency-division multiplexing (f-OFDM) sub-band and the additionalsub-band is an additional f-OFDM sub-band.
 27. The method of claim 21,wherein the default sub-band and the additional sub-band arenon-overlapping sub-bands, and wherein the second sub-carrier spacing isdifferent from the first sub-carrier spacing.
 28. The method of claim21, wherein the additional frame structure parameters include a firsttransmission time interval (TTI), and wherein the higher-layer signalingcomprises an index or value for the first TTI.
 29. The method of claim21, wherein the default sub-band and the additional sub-band occupyeither a same frequency partition within different transmission timeintervals (TTIs) or different frequency partitions within a same TTI.30. A user equipment (UE) comprising: a processor; and a non-transitorycomputer readable storage medium storing programming for execution bythe processor, the programming including instructions to: receive from atransmitter, a downlink related signaling indicating default framestructure parameters when the UE initially accesses a network; andreceive, from the transmitter, a first transmission in a defaultsub-band with the default frame structure parameters; receive, from thetransmitter, a higher-layer signaling to indicate additional framestructure parameters and an additional sub-band; and receive, from thetransmitter, a second transmission in the additional sub-band with theadditional frame structure parameters, wherein the default sub-band andthe additional sub-band are in a same system bandwidth, the defaultframe structure parameters comprise a first sub-carrier spacing, theadditional frame structure parameters comprise a second sub-carrierspacing, and wherein: the first sub-carrier spacing and the secondsub-carrier spacing both are 15 kilohertz (kHz); the first sub-carrierspacing and the second sub-carrier spacing both are 30 kHz; or the firstsub-carrier spacing is 15 kHz, and the second sub-carrier spacing is 30kHz.
 31. The UE of claim 30, wherein a bandwidth of the additionalsub-band is 5 megahertz (MHz).
 32. The UE of claim 30, wherein thehigher-layer signaling comprises an index of the additional sub-band oran offset from a reference value associated with the additionalsub-band.
 33. The UE of claim 30, wherein the higher-layer signalingcomprises an index for the second sub-carrier spacing.
 34. The UE ofclaim 30, wherein the additional frame structure parameters correspondto a first frame format assigned to a first semi-static allocationperiod.
 35. The UE of claim 30, wherein the default sub-band is adefault filtered-orthogonal frequency-division multiplexing (f-OFDM)sub-band and the additional sub-band is an additional f-OFDM sub-band.36. The UE of claim 30, wherein the default sub-band and the additionalsub-band are non-overlapping sub-bands, and wherein the secondsub-carrier spacing is different from the first sub-carrier spacing. 37.The UE of claim 30, wherein the additional frame structure parametersinclude a first transmission time interval (TTI), and wherein thehigher-layer signaling comprises an index or value for the first TTI.38. The UE of claim 30, wherein the default sub-band and the additionalsub-band occupy either a same frequency partition within differenttransmission time intervals (TTIs) or different frequency partitionswithin a same TTI.
 39. A wireless network comprising: a backhaulnetwork; and an access point (AP) communicatively coupled to thebackhaul network, the access point configured to transmit, to a userequipment (UE), a downlink related signaling indicating default framestructure parameters when the UE initially accesses a network, totransmit, to the UE, a first transmission in a default sub-band with thedefault frame structure parameters, to transmit to the UE, ahigher-layer signaling to indicate additional frame structure parametersand an additional sub-band, and to transmit, to the UE, a secondtransmission in the additional sub-band with the additional framestructure parameters, wherein the default sub-band and the additionalsub-band are in a same system bandwidth, the default frame structureparameters comprise a first sub-carrier spacing, the additional framestructure parameters comprise a second sub-carrier spacing, and wherein:the first sub-carrier spacing and the second sub-carrier spacing bothare 15 kilohertz (kHz); the first sub-carrier spacing and the secondsub-carrier spacing both are 30 kHz; or the first sub-carrier spacing is15 kHz, and the second sub-carrier spacing is 30 kHz.
 40. The wirelessnetwork of claim 39, wherein a bandwidth of the additional sub-band is 5megahertz (MHz).
 41. The wireless network of claim 39, wherein thehigher-layer signaling comprises an index of the additional sub-band oran offset from a reference value associated with the additionalsub-band.
 42. The wireless network of claim 39, wherein the higher-layersignaling includes an index for the second sub-carrier spacing.
 43. Thewireless network of claim 39, wherein the AP is further configured to,prior to transmitting the first transmission, continuously orperiodically transmit a set of default frame structure parameters intime.
 44. The wireless network of claim 39, wherein the additional framestructure parameters correspond to a first frame format assigned to afirst semi-static allocation period.
 45. The wireless network of claim39, wherein the default sub-band is a default filtered-orthogonalfrequency-division multiplexing (f-OFDM) sub-band and the additionalsub-band is an additional f-OFDM sub-band.
 46. The wireless network ofclaim 39, wherein the default sub-band and the additional sub-band arenon-overlapping sub-bands, and wherein the second sub-carrier spacing isdifferent from the first sub-carrier spacing.
 47. The wireless networkof claim 39, wherein the additional frame structure parameters include afirst transmission time interval (TTI), and wherein the higher-layersignaling comprises an index or value for the first TTI.
 48. Thewireless network of claim 39, wherein the default sub-band and theadditional sub-band occupy either a same frequency partition withindifferent transmission time intervals (TTIs) or different frequencypartitions within a same TTI.